Police received around 300 calls from the public after a new appeal for information on the murder of Jill Dando was broadcast on Crimewatch.
The names of two men were mentioned twice by callers, the police officer leading the investigation said.
Presenter Nick Ross said 183 calls had been made to the BBC studio, with 36 calls being prioritised as "very interesting indeed".
At least another 100 calls were received by the incident room in Kensington, west London, he added.
Miss Dando, 37, was killed by a single bullet to the head outside her home in Gowan Avenue, Fulham, south-west London on April 26 last year.
Detective Chief Inspector Hamish Campbell, who is leading the inquiry, had appealed for information on loners and people who may have been obsessed with guns or with Miss Dando as well as people who had the ability to be in Fulham on the day of the murder.
"People are ringing in with that sort of information - very precise," Mr Campbell said.
"A lot of names, two names have been mentioned twice and that is the sort of information we need - some new individuals' names linking directly to Jill Dando in previous relationships and that is what we are looking for."
Mr Ross said: "A year after the murder of Jill Dando, a lot of people still think that they can help."
He added that many people were ringing in with their own theories on why Miss Dando was murdered.
But he said the police had been investigating the crime for nearly a year and needed facts, not theories.
He said: "The first calls that came in from the appeal tended to be people who said 'I had a dream or I've read Tarot cards' - people with theories, but now names, and lots of names."
The programme focused on a man who was seen hanging around near Miss Dando's home on the day of her murder and on two previous Mondays.
Mr Campbell said: "I think he probably knew where she lived and was waiting for her to turn up. We know Miss Dando's movements on the previous two Mondays and she wasn't there."
A dozen witnesses say they saw a man aged in his 30s to 40s wearing a dark suit who appeared agitated.
Three of them said he wore a suit that was too big for him, three of them said he wore a trilby hat and several said he had a mobile phone.
Mr Campbell said the killer was likely to be someone with an interest in firearms and may read specialist gun magazines.
They said he may live alone and have a strong interest in Jill Dando or an unhealthy infatuation with other women.
"My view is that the interest this person has in Jill Dando would not have developed in the months before her murder. It will be somebody who has had this interest developing over some time.
"We know of people who had an unhealthy interest in Jill Dando. They have been eliminated from the inquiry but there are more out there."
And he appealed directly to the murderer to give himself up.
Mr Campbell said: "I cannot say whether his fixation is transferred to someone else. The killing of Miss Dando has not resolved anything."
Earlier police revealed a man rang a woman with the same surname asking for details about the TV presenter months before she was killed.
The woman, whose initial is J, has no connection with Jill Dando, but the man tried to extract as much information as he could.
"It was a very polite, respectful call," Mr Campbell said. "She described him as a white person with no foreign accent."
Mr Campbell said the police contacted everyone with the surname Dando to see if they had received similar calls.
That call was made in December 1998 but calls to the utilities made by a man claiming to be Jill Dando's brother were made in February 1999.
The weapon used was a rare semi-automatic 9mm pistol of a type used in the criminal underworld.
On Crimewatch Miss Dando's father, Jack, 82, spoke in public for the first time about his daughter's murder.
He said the last time he saw Jill was when he went to see an eye specialist about an operation which she had arranged for him ahead of her planned wedding.
"One of the main reasons was the wedding, and I thought that I was going to have my eyesight much better so I could have walked her up the aisle, but it didn't work out that way," he said.
Mr Dando said he was living in hope that the killer would be caught.
There have been numerous theories about the murder and Mr Campbell added: "I cannot totally rule out a contract killer but what I have described here is far more compelling."Reuse content